How to Install Marble Tile Floor: A Tumbled Stone Entryway

A tumbled marble medallion adds a distinctive tile feature to any room. The medallion is preassembled, so it's easy to install and makes a tile floor that's durable and beautiful. This story shows tiling an entryway, but you can use the same techniques in a bathroom or kitchen with equally dramatic results.

Overview of the marble tile entryway

Setting the medallion

Medallions come preassembled (halves) so all you have to do is carefully slide them in.

One look at this tumbled marble medallion and we were hooked—especially when the salesperson told us that the entire medallion came preassembled on a backer mat. All we'd have to do is install a mortar base and the floor tile, leaving a space for the round medallion, and drop the two halves in place.

In this article, we'll show you how to tile a floor that includes a centered medallion. Your local full-service tile showroom may have a medallion on display for you to look at, but most medallions will have to be ordered. Our marble medallion took four weeks to arrive.

The 12 x 12-in. tumbled limestone tiles that surround the medallion were expensive. Order about 20 percent extra to allow waste for the diagonal cuts. You could also use one of the many other floor tiles that look like stone (and are much less expensive!). Just make sure whatever floor tile you choose is about the same thickness as the medallion.

Even though the medallion is preassembled, you should have some tiling experience. Plan on spending a couple of weekends to complete a project like this.

Floor prep 1: Eliminate the floor bounce

Photo 1: Tear out old flooring

Tear out old hardwood flooring, ceramic tile or carpet and underlayment to allow extra room for the mortar bed and tile. This will minimize level changes at the openings into other rooms. Cut flooring or underlayment into smaller pieces to make them easier to remove. Make sure to leave subfloor fully intact. Use a large pry bar for extra leverage.

Photo 2: Clean and prime the subfloor

Prepare the area for the self-leveling mortar bed. Protect woodwork with masking tape. Cover heat ducts with blocks of rigid foam and seal around them with duct tape. Cover the seams between sheets of plywood with masking tape. Plug all holes with tape or expanding spray foam. Prime the floor according to the instructions on the bag containing the self-leveling mortar.

Photo 3: Staple down metal lathe

Cut sheets of Expanded metal lath with a tin snips to fit around obstacles and between walls. Allow each piece to lap over the previous one about 2 in. Secure the lath to the floor with 1/2-in. staples placed about 6 in. apart. Staple from the center of the sheet to the outside to eliminate bulges.

For your tile to last, it has to be installed on a strong base. Here are a few of the common types of floor construction you might have and what you must do to get them ready for tile:

If you have wood floor framing
First jump on your floor to check for bounce. It's a judgment call, but if it moves much, stiffen it by adding posts and beams under it or by reinforcing the floor joists (the wood framing that supports your floor).

Next, peer alongside a heat duct or drill a 3/4-in. hole in the floor to determine how many layers of flooring there are and how thick each is. The self-leveling underlayment we're using requires a minimum of 3/4-in. thick boards or plywood under it. If you have less than that, glue and screw another layer of 1/2-in. plywood over the existing floor.

If your subfloor (the lowest layer next to the joists) is covered with any flooring material or underlayment, like particleboard, 1/4-in. plywood or even ceramic tile mortar, tear it out to make room for the tile and self-leveling underlayment (Photo 1). Caution: Sheet vinyl or vinyl tiles may contain asbestos. If you must tear out a vinyl floor, call the U.S. Consumer Product Safety Commission for information on testing for asbestos and guidelines for safe removal. Its Web site is www.cpsc. gov.

Concrete floors are a great tile base
You can glue the tile directly to concrete, but it has to be clean and structurally sound. Ask a knowledgeable tile salesperson for specific instruction. If the concrete has cracks, the tile you lay over it can also crack if the concrete isn't stable. Play it safe. Install a special isolation membrane between the tile and the concrete. The membrane prevents any movement in the cracked concrete from cracking the tile. Some membranes are liquids that are painted over the crack. Others are sheets of rubber that you glue down over the crack. Consult your salesperson, a tiling book or tile installer for more information on the various types of isolation membrane and how to install them.

There are many ways to deal with level differences
New tile almost always raises the floor height. You might have to trim door bottoms and install special transition pieces at doors and openings. Rather than install a wood or plastic transition, we made our own bullnose tile by rounding the cut edges of the limestone with 80-grit sandpaper. Larger level differences may require stone, plastic, metal or wood transition pieces. A tile dealer will stock a wide selection and help you plan them.

Floor prep 2: Apply a strong base

Photo 4: Pour leveling underlayment

Pour the self-leveling mortar underlayment around the perimeter. Then quickly fill in the center, working toward your mixing area. Have a helper continue the mixing process. Use a trowel to help the mortar into corners and around obstacles. Work quickly. Reach out and spread the mortar with a trowel as you work your way out of the room. Then leave it alone as it levels out and hardens.

The second step for a durable tile floor is to apply a strong, level, tile-setting base. In the old days, there was no choice of base material. It was always a thick (1 to 4 in.) layer of mortar that required a skilled craftsman to install. Then came 3 x 5-ft. sheets of 1/2-in. thick cement board; these were easier to install but still not perfect. The boards follow the contour of the floor, which does nothing to correct crooked or out-of-level floors.

Instead we used a relatively new type of tile base called self-leveling underlayment. It's basically mortar with latex additives and you mix it with water. It can be mixed up soupy enough to pour from a bucket and yet is extra strong when it hardens. You don't need any special skill to pour a perfectly smooth and level floor, and you don’t have to fool around with cutting cement board. You’ll find 25-lb. bags of self-leveling underlayment powder at full-service tile shops and most large home centers. The manufacturer suggests a minimum thickness of 3/8 in., but to be safe we poured our underlayment 1/2 in. deep. For 1/2-in. depth, you'll need one bag for every 12 sq. ft. of floor. You'll also need primer to seal the wood subfloor (check the underlayment bag for the exact type) and expanded metal lath to reinforce the mortar. Sheets of metal lath are usually 30 x 84 in. and are available where you buy your other tile supplies. Buy enough to cover the entire floor, plus about 10 percent extra to allow for waste.

Photos 1 - 4 show how to prepare the floor and pour the mortar underlayment. Mixing and pouring the self-leveling underlayment is as easy as it looks, but there are a few things to watch out for.

The self-leveling underlayment we used starts to harden in about 10 minutes at 70 degrees F, and even faster if it's hotter. (Some products are formulated to give you a little more time; check the bag to find out.) The secret to success is having everything ready to go. Before you start mixing, measure the exact amount of water into five or six 5-gal. buckets, open all the bags you'll need, and have extra water and the measuring bucket handy. Then have a helper mix while you pour. The two of you should be able to mix and pour a bag every minute; that's plenty of time unless you have a very large floor.

Clean the tools and buckets right away. Then let the underlayment harden overnight before you tile. Tip: For a better gauge of thickness, use a 4-ft. level to set up a grid of drywall screws with the heads level with the desired top surface. Then pour the mud even with the top of the screws and remove them after it hardens.

If you return the day after pouring to find some low spots in the floor, don't panic. We had this problem and fixed it by priming the underlayment and pouring another 1/8-in. layer to fill the low spots.

Floor prep 3: Lay out the medallion and tile positions

Photo 5: Make a cardboard template

Stretch a length of 14-gauge stranded wire around the medallion and trace around it with a pencil. Carefully cut along the line with a sharp utility knife to make a cardboard template that includes a 1/8-in. grout joint (the thickness of the wire). Use thicker wire for larger grout joints. Mark the medallion and the cardboard with two reference points labeled “1” and “2.” You'll use these reference marks later to align the medallion with the cut tile.

Photo 6: Center the medallion

Snap a chalk line down the center of your room, parallel with the most visible wall. Use a framing square to make a line perpendicular to the first line, centered on your proposed medallion location. Center a block of floor tile on the lines and set the template over them to see how the cut tiles around the medallion will look, and how the medallion looks in the room. Now extend tiles to the edges of the room to see what size the border cuts will be. Adjust the location of the medallion if necessary to improve the look of the border tile.

Photo 7: Mark a square tile grid

Make a diagonal grid of tile guidelines. First draw a 3-ft. square and connect opposite corners to establish the diagonal reference line. Then use this reference line to establish the 24-1/4 in. square grid (two 12-in. tiles plus two 1/8-in. grout lines). To avoid confusion, mark around the center tile to indicate the center of the medallion.

Before you start tiling, you'll have to snap chalk lines on the floor to keep the tile in alignment. This process of laying out the tile is half mathematical and half aesthetic. The goal is to arrive at a starting point for the tile that leaves nice-size cut pieces around the edge of the room. Unless you're really lucky, though, you'll have to make a few compromises. The trick is to position the layout so small pieces, or ones that are tapered because the room isn't square, are in the least conspicuous spots. Arranging the actual tiles, including the spaces between them for grout, is the most foolproof method of laying out tile. You could also make a scaled drawing on graph paper to get a preliminary idea of how the tile and medallion fit on the floor.

Photo 6 shows how to start the layout by positioning the medallion and extending the tile out to the edges of the room. This allows you to see what size the cut border tiles will be. You may be able to shift the location of the medallion slightly to improve the look of the cut border tile. We moved the medallion 1/2 in. closer to the front door to avoid being left with a tiny triangle of tile.

Once you determine a starting point, the rest is just a matter of snapping chalk lines (Photo 7) to form a diagonal grid. Each square of the grid contains four tiles, and the distance between the lines is equal to the width of two tiles and two grout joints. It's simple to keep track of where the grout joints are if you place an “X” in the same corner of every box, and always start tiling by aligning both edges of the tile with the lines forming this corner.

Tiling 1: Precut the field tiles along edges

Photo 8: Position the tile and mark cuts

Measure for the cuts on the border tiles. Align full tiles with the grid marks, and measure from these to the wall, allowing space for grout.

Photo 9: Mark the tiles

Measure and mark the tile. Then make a diagonal cutting line across the mark with a Speed square. Number the tiles on the back so you can precut and position them correctly when you're ready to install it.

Photo 10: Cut the tile

Saw along the line with the wet-cutting diamond saw. Wear safety goggles and hearing protection. Steer the tile along the line as you slowly push it into the blade. Make very subtle adjustments to avoid binding the blade.

Photo 11: Undercut door trim

Saw off the bottom of door trim or door jambs so the tile will slide under them. Set a floor tile on a piece of cardboard to guide the saw cut. Use a saw with sharp, fine teeth. Remove the cutoff chunk of molding with a screwdriver or small chisel.

Photos 8 - 13 show how to measure, mark and cut the stone tile. Diamond blades make this process as easy as sawing wood. Most rental stores and tile shops have a wet-cutting diamond saw like the one shown in Photo 10 available for rent. Water is pumped onto the blade to keep it cool and keep dust to a minimum. You'll still want to set the saw up outside or in the garage, though, since the blade throws out a fine mist of dirty water. Ask the rental store for instructions and safety precautions to follow when you're using the saw.

With the grid marked on the floor, it's an easy matter to cut all the tiles before you spread any adhesive. Be sure to number the backs of the tiles with a pencil so you'll know where they go. Leave the cut tiles in place, and move them out of the way just before you spread the thin-set on each section.

Tiling 2: Precut the field tiles around the medallion

Photo 12: Mark the medallion perimeter

Align a block of floor tile with the grid lines. Include exact grout spaces. Tape the cardboard template to the tiles, making sure the space around the edges is even. Draw around the template with a pencil. Transfer the two reference marks (Photo 5) to the tile. Number the template for each tile and mark the back of each tile with the corresponding number.

Photo 13: Cut the curves

Make curved cuts using a dry-cut diamond blade mounted in a 4- or 4-1/2 in. grinder. Firmly clamp the tile to a piece of plywood laid over sawhorses. Wearing a dust mask, hearing protection and safety goggles, score along the line with the diamond blade. Use a shop vacuum to collect the dust and chips. Make three or four passes with the grinder to gradually saw through the tile. Round over the cut edge of the tile with 80-grit sandpaper.

We used a grinder equipped with a dry cutting diamond blade to make the curved cuts (Photo 13). Purchase a grinder or rent one. We bought the diamond blade at a home center.

Tiling 3: Set the field tile

Photo 14: Spread thin-set mortar

Mix thin-set mortar according to the instructions on the package to the consistency of peanut butter. Trowel a layer of thin-set up to your layout lines, covering about 6 or 8 sq. ft. Press the thin-set onto the mortar bed to form a good bond. Go over the entire area with the notched trowel held at 45 degrees to the floor to create an even layer of ridged thin-set.

Photo 15: Set the field tiles

Wiggle and press each tile into place to ensure a good bond. Start by installing a corner tile at each position marked with an “X,” aligning two edges with the corner formed by the two layout lines. Now lay the remaining tiles to fill between these corners, spacing them evenly. Complete each small section before moving on. Stand up occasionally and scan the floor for misaligned tiles. Use the round cardboard template to check the positioning of the tiles around the medallion space. Let the adhesive dry overnight.

Install all the tile and let the adhesive harden overnight before installing the medallion. Use the cardboard template to precisely position the curved tiles that surround the medallion.

Follow Photos 14 and 15 and these tile-setting guidelines.

Use white multipurpose thin-set mortar adhesive to glue the tile to the floor (Photos 14 and 15). Standard gray thin-set will stain some light-colored stone and can show through light-colored grout.

Mix the thin-set to the consistency of toothpaste according to the instructions on the container.

Mix only as much thin-set as you can use in about an hour. Restir it occasionally to keep it workable, but never add more water. Discard the thin-set and mix a new batch if it starts to harden.

Test to make sure you're putting enough thin-set on the floor by pressing a tile into the freshly troweled thin-set and pulling it off to inspect the backside. It should be fully covered with thin-set. If not, use a larger-notched trowel or increase the angle of the trowel when you’re spreading to leave more thin-set on the floor.

If a tile sinks below its neighbor (check with the flat edge of your trowel), lift it out and “butter” the back with more thin-set, then reset it. Use a margin trowel to lift the tiles and butter the backs.

Keep a bucket of water and sponge handy to clean thin-set from your hands, tools and tile before it hardens.

Clean excess thin-set from between tiles with a margin trowel or utility knife before it hardens.

Tiling 4: Set the medallion tile

Photo 16: Slide the medallion into place

Slide each half of the medallion gently onto the freshly spread thin-set, making sure the reference marks are aligned. Use a thin sheet of plywood to support the medallion as you slide it off. Carefully align the sections. The medallion should be sitting slightly above the surrounding tile.

Photo 17: Flatten the medallion

Press the medallion into the thin-set to embed it and bring it flush to the surrounding tile. Use a straight board or level to tamp over the entire area. If you need to raise or lower pieces or sections of the medallion, cut through the mesh backing with a utility knife before lifting them out. Then add or remove thin-set to bring the pieces to the proper level.

Photo 18: Clean between tiles

Scrape the excess thin-set from between the pieces of marble with the point of a utility knife. Use a sponge to collect excess thin-set and clean the face of the tiles as you go. Allow the thin-set to harden overnight.

Scrape and sweep the floor where the medallion will go. Before you spread any thin-set, set the medallion in place to check the fit and get a feel for how much thin-set you'll need to hold it up flush with the surrounding tile. If it’s about 1/8 in. too low, you'll be able to use the same 1/4 x 3/8-in. notched trowel. If it's lower, use a 1/4 x 1/2-in. trowel; higher, a 1/4 x 1/4-in. The goal is to slide the medallion into the thin-set and have it sit a little higher than the surrounding tile. Then press it down flush (Photo 17) without too much thin-set oozing out.

Remove the medallion, spread the thin-set and slide one half of the medallion into place (ours came in two pieces). Then slide the other half into place and tamp it down (Photo 17). Clean out the excess grout (Photo 18) and gently reposition tiles that look out of place. If you have to reset a tile or add thin-set under it, cut through the mesh backing with a sharp utility knife before you lift it out. When you're happy with the way the medallion looks, let the thin-set harden overnight and you're ready for sealing and grouting. Tip: Lock the front door, put pets in the basement and erect barricades to keep “tourists” from testing your floor.

Tiling 5: Seal the tile and grout the floor

Photo 19: Seal the stone

Seal the porous surface of the stone with liquid stone enhancer to simplify grout cleanup and enliven the color. Spread the sealer and allow it to soak in about a half hour. Then clean up the excess with an old bath towel and allow the sealer to dry according to the instructions on the container. Read the label and follow all safety precautions.

Photo 20: Spread the grout

Mix grout according to the instructions on the package. Press it into the spaces between tiles with the rubber face of the grout float. Work the trowel back and forth to make sure the grout is tightly packed into every space. Complete all the grouting steps, including cleanup with a sponge, on a small section of floor (about 16 sq. ft.) before moving on to the next section.

Photo 21: Clean the surface

Clean the grout film from the face of the tile with a special grout sponge. Allow the grout to “firm up” in the joint before cleanup. Do not allow the grout film to harden or dry on the face of the tile. It will be very difficult to remove. Start by scrubbing the face of the tile with a wrung-out sponge, rinsing the sponge in clean water when it fills with grout. Complete the cleanup process by making long overlapping swipes, using a clean face of the sponge for each pass. Polish the tile with a soft cloth to remove dried grout haze.

To enhance the color of the stone and make grout cleanup easier, we applied a liquid stone enhancer before grouting (Photo 19). Even if you like the more subdued color of the unsealed stone, ask your salesperson to recommend a “grout release”-type sealer to keep the grout from sticking to the face of the porous stone. Follow the instructions and safety precautions on the label.

When the sealer is dry, you're ready to grout. Buy sanded grout for use on floors and read the instructions to see if the powder should be mixed with plain water or latex additive. Tip: Glue leftover tile scraps to a piece of plywood, grout them, and let the grout dry to make sure you like the grout color.

Photos 20 and 21 show how easy grouting is, but don't be fooled. All the tile pros I know have a horror story about spreading more grout than they could clean up before it hardened. Avoid this problem by completing 4 x 4-ft. areas before moving on. Also be aware that grout sets much faster in hot, dry weather. Dampen the surface of the tile with a sponge before grouting to make cleanup easier. Use a special grout sponge, available at tile supply stores, and keep it clean and wrung out. Using too much water will weaken the grout and cause uneven grout color.

After the final cleanup (Photo 21), let the grout dry overnight. Then remove the remaining haze by polishing with an old bath towel. Allow the grout to dry for 48 hours. Then paint grout sealer onto the grout joints with a disposable sponge applicator. This will help prevent dirt and stains from permanently discoloring the grout and will make cleaning easier.